Joe Curry wrote :
>
> The only things that Ted left out is compensation for thickness
> of the head gasket and the amount the piston sticks out of or
> rests below the surface
> of the deck.
Joe, you beat me to it. AFAIK all TR-series cars had flat-top pistons that
nominally come flush with the top of the block at TDC. This may change of
course if the block has been machined, or the rods, pistons and/or crank are
not stock. However, many Spitfires did not (as Joe knows well), there may
be others. Both the shape of the piston top, and it's location in the
cylinder at TDC have to be taken into account when computing compression
ratio. One way to do this is take Ted's measurement of cylinder volume at
BDC, and compare it to the calculated swept volume (bore x bore x stroke x
Pi / 4). Any difference, either positive or negative, must be taken as an
adjustment to the measured combustion chamber volume.
Randall
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